Base for incandescent lamps and similar devices



ug- 1940- c. A. BROWN ET-AL 2.210.525

BASE FOR INCANDESCENT LAMPS AND SIMILAR DEVICES Filed May 14, 1938 In vencofs: Carl A.-Br-own, 2 Clarence E.-Hahn, by A T 'eir Attorney.

Patented Aug. 6, 1940 PATENT OFFICE BASE roa INCANDESCENT rams AND SIMILAR DEVICES Carl A. Brown, Char-don, and Clarence E. Hahn, Cleveland, Ohioyassignors to General Electric Company, a corporation of New York Application May 14, 1938, Serial No. 207,964

6 Claims.

10 the bottom end or center contact consists of a small brass eyelet mounted onthebase insulation, to which eyelet one of the filament lead wires is soldered. Although this form of end con-- tact has proven satisfactory, still the elimination 15 of the use of the brass eyelet is a high1y desirable feature in view of the resulting saving in brass and reduction in the cost of base manufacture. While the elimination of the brass eyelet has been heretofore proposed by the use of simply a quantity of solder or other suitable conductive material as the end contact, the results therefrom have not been entirely satisfactory for the reason that the solder does not completely fill the recess provided therefor in the base insuation. As a 25 result, the pressure exerted on the solder by repeated insertion of the lamp into its socket forces thesolder to flow into the unfilled portions of the recess, thereby lessening the initial 1 assembled height of the solder above the base 30 shell and base insulation to the point where engagement of the solder end contact with its corresponding socket contact is oftentimes entirely prevented. I

One object of our invention is to provide an 5 electric incandescent lamp or similar device in which the customary base end contact eyelet is eliminated and a quantity of conductive fusible material employed as the end contact.

Another object of our invention is to provide 40 an electric incandescent lamp or similar device with a bottom end contact consisting solely of a globule of conductive-and readilyfusible material which will maintain its originally assembled height above the base shell and base insu- 45 lation. 7

Still another object of our invention is to provide a lamp base with'a recess in the insulation thereof of such shape as to substantially conform to the contour of a drop of solder or other 50 fusible material, whereby-the said material comv pletely iillsthe recess.

Further objects and advantages of our invention will appear from the following description of a species thereof and from the accomu. panyin: drawing in which:

, Fig. 1 is a side view, partly in section, of an electric incandescent lamp provided with a base end contact comprising our invention; Fig.2 is an enlarged fragmentary sectional view of the base end of the lamp shown in Fig. 1; Fig. 3 is a 5 plan view of a. preformed insulator button for a lamp base provided with a recess shaped according to our invention; and Fig. 4 is a sectional view' taken on the line 4--4 of Fig. 3.

Referring to the drawing, there is shown in 10 Fig. 1 an electric incandescent lampcomprising a bulb l0 having a filament (not shown) sealed therein and a base Ii attached to the neck I2 .01 the bulb by suitable cement i3. The base ll consists of a threaded metallic shell l4, preferably of brass, together with suitable insulation l5, preferably of glass, and a bottom end contact l6. One end of the lamp filament is connected to the base shell I4 by means of a lead Il bent back over the end of the bulb neck and soldered so at l8 to the edge of the said shell. The other end of the lamp filament is connected to a lead 19 which extends through a centrally located opening 2|! in the glass insulation l5into a recess 2| in the upper surface of the glass insulationwherethe said lead is secured by means of a drop of solder l6 or other similar fusible material to thereby form the lamp end contact. The glass insulation i5 is preferably made as a preformedbutton and is provided with a plurality of projections 22 (Figs. 2' and 3) on its upper surface and adjacent its periphery, as described and claimed in our copending application Serial No. 207,965, of even date herewith These projections are formed with arcuate sidewalls 23 which are engaged by a reentrant flange 24 on the base shell I4 to firmly secure the glass button and shell together and to lock the same against relative rotational displacement, as disclosed in the aforesaid co-pending application.

To insure the complete filling of the recess 2| by the solder IS, the said recess is made substantiallysemi-globular in shape and of such size as to conform as closely as possible to the natural shape of that portion of the dropof solder which is to be inserted therein. With such a shaped recess there are no sharp corners which might remain unfllled'by. reason of the sudden cooling of the solder forming the end contact. Consequently, there are no unfilled spaces into which the 5 solder might be forced to flow by the pressure exerted thereon during repeated insertion of the lamp in its socket, and therefore the initially assembled height of the solder above the base shell I4 and the glass button II is maintained at all ll contact of the lamp socket, thereby preventing completion of the circuit through the lamp filament and so foreshortening the useful life of the lamp.

As shown in Fig. 2, the solder l6, when inserted into the recess 2!, flows-down into the opening 20 so as to partially fill the space between the wire l9 therein and the walls of the said opening. The wire I9 being tinned, the solder readily ad- I heres thereto and so becomes firmly bonded to the said wire. Because of this firm bond, and further because of the minuteness of the space (approximately 0.010 of an inch) between the wire i9 and the walls of the opening 20, no movement of thesolder down through the opening occurs when pressure is applied to the outer surface of the globule of solder It, so that the originally assembled height of the solder it above the base shell M and the glass-insulation i5 is therefore maintained.

As will be noted particularly in Figs. 3 and '4, the recess 2i is provided with a small annular ridge around the edge of the opening 28. This annular ridge is formed during the prefabrication of the glass insulator button IE, by the plunger which forms the hole 20, and is a result of the carrying of a portion of the molten glass by the plunger down into the recess provided in the preforming mold for accommodation of the -said plunger, said recess being slightly larger in diameter than the plunger. As a consequence of this particular method of formation of the ridge 25, the upper surface 26 thereof is very ragged or irregular, as shown in Fig. 4. This irregular surface 26 therefore serves to-prevent undesired rotation of the solder it within the recess 2i when the lamp is screwed into a socket.

While the recess 2! and the drop of solder it forming the lamp end contact are shown applied to a preformed insulator button IE, it is obvious that the same may be applied equally well to bases as made by the present method which consists in forming the glass insulation on the base shell while in a molten state.

. What we claim as new and desire to secure by 5.) Letters Patent of the United States: is:

1. An electrical device comprising abulb having an electric energy translation element sealed therein and a base mounted thereon, said base comprising a metal shell, an insulating member secured to an end of said shell and provided with a concave substantially semi-globular recessin its outer surface, and an end contact mounted on said insulating member, said shell and end contact being connected to opposite ends of said on electric energy translation element, said end con.-

tact consisting of amass of readily-fusible con-' ductive material disposed within the said recess. in direct contact with said insulating member and entirely filling the said recess. 55 2. An electrical device comprising a bulb hav' ing an electric energy translation element sealed therein and a base mounted thereon, said base comprising a metal shell, an insulating member secured to said shell and provided with a substantially semi-globular recess in its outer surface and an annular ridge having an irregular end contact consisting of a mass of fusible conductive material disposed within the. said recess and entirely filling the same, the irregular surface 'of said ridge being in interlocking engage- I ment with said end contact to prevent rotation of said end contact within said recess.

3. A base for electric lamps or similar devices comprising a metallic shell. and an insulating member secured to an end. thereof, the outer 1 surface of said insulating member being provided with a centrally located concave and substantially semi-globular recess for direct reception of a quantity ofreadily fusible conductive material.

4. The method of basing anelectrical device comprising a glass bulb having a pair'of leadin wires extending from an end thereof, which method comprises forming a button of insulating material with engagement means at its periphery and a sub-globular-recess in its upper surface, uniting said button at its rim to the upper end of a metallic base shell so as to form an interlocking engagement between the end of said shell and the said engagement means on said button to secure them against relative axial and rotative movement, uniting the said base shell at its lower end to the end of said bulb, connecting one of said lead-in wires electrically to said base shell, extending the other lead-in wire to the said recess in said insulating button, and forming an end contact by placing a drop of readily fusible contact, said recess having therein an annular ridge with projections thereon serving to look a contact filling said recess against rotation withinsaid recess. v

6. An electrical device comprising a. bulb having an electric energy translation'element sealed therein and abase mounted thereon, said base comprising a metal shell, an insulating member secured to an end of said shell and provided with a substantially semi-globular recess in its outer' surface, said recess having projections protruding from its surface, andan end contact on said insulating member, said shell and end contact being connected to said electric energy translation' element, said end contact consisting of a mass of fusible conductive material disposed within the said recess and entirely filling it, said projections being in. interlocking engagement .with said end contact to prevent rotation 0 said end contact within said'recess. 1

CARL A. BROWN. 

